Space-Time Hero Protocol
by Blue Teller
Summary: Class 1-A discusses space-time travel: what kinds there are, what dangers, and how to handle them. What, you really thought the world of heroes wouldn't have proper protocols to deal with time travel? Also, Aizawa might be a bit more familiar with the topic than his students think...


"Today," Mr. Aizawa starts with his usual deadpan expression "We'll be talking about Space-Time Hero Protocol."

All the students immediately perk up.

"Alright!" cheers Kirishima.

"So cool...!" Kaminari whispers to Sero, excited.

"You think we'll get an actual demonstration?" Yaoyorozu wonders aloud.

"-what I remember there are 13 different kinds of space-time travel where in each instance cause and effect have proportionally different relativity-" Midoriya is already muttering to himself making notes.

"First," Aizawa continues unperturbed, having anticipated the reaction "We will discuss the different kinds of space-time travel. Then we will continue with the Hero Protocol for experiencing unexpected or unauthorized space-time travel, and the next class we will finish the topic with current laws concerning each type. So. Does anyone know what was the first type of space-time travel registered?"

"Time loops!" Ashido waves her hand in the air with enthusiasm.

"Parallel timelines?" Uraraka sounds uncertain.

"Shadow realities," Tokoyami says ominously.

"All quiet! Wait for Mr. Aizawa's permission to speak before you do!" Iida exclaims, waving his hands and chastising his fellow classmates.

"You're being too loud, Iida," Aizawa deadpans at him.

"I apologize, sir!"

"It's fine. Does anyone actually know, are you going to keep guessing?" The vice-president raises her hand. "Yaoyorozu."

"Space-time travel across small distances, sir. The second one was across large distances."

"Thank you. The rest of you seem to have forgotten the 'space' aspect of space-time travel. Yes, traveling across space only still counts. Now, what is the difference between small and large distance travel, and why is there a distinction in the registry?" He nods towards the green-haired student. "Midoriya."

"Small distance travel is the travel within the same city where you can return to your previous location without outside help, like on foot or with public transport," Midoriya shoots off with enthusiasm. "While in large distance instances you can land outside your region or even your country and the retrieval process is more complicated because of it!"

"Correct. Though in some cases what counts as small or large distance might be unclear – work areas of heroes can have very different scopes depending on their specialties – usually it implies that small distance is a lot less trouble than large distance. There are a lot less quirks capable of large distance travel, but as you all know, it's not unheard of. The League of Villains, for instance, have means to instantly relocate big groups of people without any difficulty."

"The warp guy," Bakugo sneers, speaking for the first time since the start of the class.

"Exactly. Most large distance quirks are automatically capable of small distance travel... however, there was once a quirk registered where a man was able to travel only to the exact opposite side of the Earth, and nowhere else. The flexibility might vary. Still, all space-time quirks are considered potentially extremely dangerous and demand high discipline and training, and any unexpected and unauthorized travel can cause a big amount of problems."

"Um, Mr. Aizawa?"

"Yes, Asui."

"I was wondering, why is sole space travel included in the space-time laws? Shouldn't it be its own category, if it doesn't affect time in any way?"

"A valid question. Does anyone have any ideas?"

"Oh! I have one!" Hagakure waves her sleeve above her head. "It's because technically you still lose time because of the travel, right? Since you have to waste time getting back to your previous location?"

"Close, but not quite. Anyone else?" A dual-haired boy slowly raises his hand. "Todoroki."

"Since it's instantaneous traveling across space, it can technically still be a type of time travel, right? Because there might be a split second when you teleport and stop existing... or you appear faster than you disappear."

"A better answer. Since space manipulation can be very volatile, it more often breaches onto the time territory than not. Sometimes what seems to be mere teleportation might turn out to actually be time travel and vice versa."

"But how do we know for sure?" Mineta asks a little nervously.

"Identifying the type of space-time travel is often problematic, especially without proper equipment. Which is why it's important to pay close attention to recognize the sighs. When it comes to proper time travel, the simplest and most common kind is what we call the closed loop timeline."

"That's what I said!" Ashido speaks in a loud whisper to her friends.

"Now, there are two kinds of closed loops. Who can tell me..." Most people raise their hands. "Ojiro."

"Well, it's either into the future or the past, right?"

"Almost. We separate them into forward and backward loops. Since time is relative, our point of reference to the present is different depending on where we start. It's important not to get confused, even if in most convoluted cases that can be extremely difficult. Why is a closed loop the most simple one? Jiro."

"Because we don't have to worry about paradoxes and changes to our timeline, since everything already happened."

"Precisely. If we know that our presence will not cause any damage, we can act without restrictions. In case of forward closed looping, people often have access to the information on whether or not they get back and how it was done. In backward closed looping it is a little more complicated, but sometimes we already know how things will play out."

Aizawa clears his throat.

"Now, shadow realities. This one is a little more ambiguous territory than the rest. The gist of it is that sometimes, heroes cannot determine if something that occurred really happened in our reality or in another if all traces are gone. Sometimes, what one perceives as a shadow reality can be the effect of a mind quirks used against them."

"Spooky," Sero whispers with a shudder.

"We had multiple such cases in the past. When it was over, no one could keep track or properly investigate. Sometimes even the quirk users themselves can't decide if their quirk actually gives them access to a new reality, creates one, or if it's a very elaborate illusion. All uncertain scenarios fall into the shadow reality category, so it is a very broad definition. It can deal with past, present, future, or any alternate reality."

"But then... isn't all time travel like that?" asks Uraraka. "Or at least it doesn't usually traces, right?"

"That is incorrect. There is technology that can keep track of some time travel types. It is kept quiet from the public for a reason. But that is for another class."

The class erupts in excited whispers.

"Quiet." Eraserhead's eyes flash read, and the students quickly fall silent. "Now, splitting timelines. There have been very little evidence of it, but there had been registered quirks that claimed to be capable of it. The catch is that once you split from the current timeline, there is nothing you can do to go back to your own." There is a moment of silence. "Whether or not our own timeline has been split from another had been a topic of debate for decades, but even if it is, personally I don't believe it matters. Split or not, we have responsibilities to our own timeline. So even if creating a new one is possible to achieve, intentionally running away from our own is selfish, even if it is done with the most noble of intentions."

The students gulp nervously at the stern tone of Aizawa.

"Next we have parallel timelines," he continues in a less severe tone. "Once again, we have two types. Anyone?"

Shoji lifts three of his right hands.

"Go ahead."

"Identical and differentiating parallels, sir."

"Very good. Like with distance travel, it can be sometimes difficult to determine. However, in both cases the other reality must have the same physics as our own. In an identical parallel timeline, we might be in the wrong time period, but things such names of people and places should remain the same. If they differ significantly – such as a large portion of history missing, people having new names et cetera – it means we are dealing with a differentiating parallel, and our knowledge of the rules and social structure might not be accurate there."

Iida stiffly raises his hand.

"Yes, Iida?"

"Then what shall we do to ensure we don't accidentally break the law of a differentiating timeline, sir?"

"We'll get to that soon with the hero protocol. Another type of space-time travel we have to address is dimensional travel. Although each instance has been kept very, _very_ top secret, it has happened several times: either a visitor from another dimension stumbled across our own, or we temporarily lost someone from our reality into theirs."

"No way!" Kirishima says, eyes shining.

"Seriously?" Even Bakugo seems interested.

"Actual aliens?!" Ashido's jumping in her seat. "How come it was never in the news?"

"Like Mr. Aizawa said, apparently it was always kept top secret," Yaoyorozu commented. "It could cause wide-spread panic if people believed we were under an alien attack."

"Mr. Aizawa?" Midoriya lifts his hand tentatively. "You said temporarily lost. It means all of them made it back okay, right?" Some of the students look concerned at well.

The teacher nods. "They did. At least, all that we are aware of."

"Thank goodness," says Uraraka in relief.

"Now, I have to address that even though calling dimensional travelers aliens is technically correct, it can cause misguided assumptions," Aizawa speaks over the students, gathering their attention. "The main thing that sets differentiating parallel timelines and other dimensions apart, is that while some of their reality can be similar, in some areas their physics can be completely unrecognizable. For example, if we have a world where quirks never came to be, but until a certain point our histories were the same, then it's a differentiating parallel. If quirks exist and the history is about the same, but also most of the population possesses magical familiars they carry around in red-and-white ball containers in their pockets – then it's another dimension."

Koda perks up with interest at the last part.

"✧How elegant~!✧" Aoyama says with a wink.

"Wait, Mr. Aizawa," Midoriya raises his arm again. "Is that a hypothetical scenario, or a real example...?"

Aizawa's face is expressionless. "Top secret."

"But-!"

"Anyway," the teacher continues, despite Midoriya's confusion. "Dimensional travelers can be as human as we are, or they could be another species, but whichever the case is, we must treat them equally with caution and respect whenever they appear. We have yet to meet an alien species that is entirely hostile and unreasonable, so assuming their morality based on actions of the few is illogical. Still, we must remember that just as humans of our world are capable of great and terrible things, so are they."

"So we have to be wary of them, but never attack without provocation," Todoroki concludes.

"Well put. Never attack first. Never engage, unless you have absolutely no other choice, because you never know what kind of power-scaling they have in their dimension." Aizawa looks at them with a hard expression. "Take my power, for example. Why would I be at a possible disadvantage in a fight against a powered individual from another dimension?"

"Oh! I know!" Sato, glad he finally has something to say, waves his hands. "Your quirk is Erasure, right? It works against quirks in our world. But you can't be sure it would work against a quirk from a different world."

"Yes, it's very possible it wouldn't. My quirk works specifically against the quirk factor – if they use something that isn't strictly a quirk in another dimension, my power will certainly be useless against it."

"Or you could just blow the bastard up," Bakugo mutters.

"Bakugo, no" Kirishima whispers to him with a frown.

"I could!" He crosses his arms in defiance.

"Mr. Aizawa just said we gotta respect aliens, not pick fights with them."

"Well if they want to fight me, I'm gonna blow them all up."

"Come on, man..."

Aizawa, used to their antics, carries on:

"And lastly, we have three types of complex time travel: dynamic, stacked, or fusion looping. Those are the most headache-inducing kinds, so pray you never encounter them." Their homeroom teacher actually looks pained at the thought. "The dynamic loop is when one or more individuals repeatedly live through a certain period of time, until a trigger releases them and returns them to the proper timeline. It leaves the least amount of collateral damage, however it can be deeply traumatizing for the ones actually experiencing the time loop. Some villains used it as means to torture heroes into suicide."

"Oh," Sero says glumly, as he has been about to comment that looping seems kind of cool.

"Stacked looping is even more troublesome. Instead of time refreashing every time the loop repeats, the changes stay, which can cause multiple copies of the same person appearing in the same place, causing all sorts of dangerous paradoxes."

"Wait, so interacting with yourself really makes the world explode or something?" Kaminari says with apprehension. "I thought that was just movie stuff!"

"It doesn't if it's a closed loop," Iida explains. "But dynamic loops are breaking rules of a stable timeline, making the cause and effect invalid in the process."

"Thank you, Iida. And lastly, fusion looping. It's just as obnoxious as the other two, except the looping affects itself in the process. It can be easier to resolve if you can get to the source of the loop, but it has the highest chances of causing permanent damage to the participants and the timeline. It's the least recommended method of time travel, so DO NOT attempt it. **Ever**. If anyone of you do, I will expel everyone here on the spot."

Asui puts a finger to her chin. "Um, Mr. Aizawa? Isn't that a little unfair?"

"When it comes to space-time safety, you have to take collective responsibility."

They sweat nervously.

"Yes, sir, Mr. Aizawa!" The students say together.

"And finally, we arrive at the protocol. Picture this scenario: you are fighting with a villain with an unknown quirk, but it allows him to vanish things into thin air through touch. You make a mistake, and they touch you. Suddenly, you find yourself in an unknown location. What is the most important thing? Uraraka."

"Checking your phone and if it works?" asks the girl. "So you can call for help... if it's just a distance travel, I mean."

"Good guess, but something else comes first. Tokoyami?"

"Assessing your surroundings for an incoming attack," the bird-headed boy proposes.

"That is the second step. Yaoyorozu."

"Staying calm."

"Very good. The first rule of space-time travel is, do NOT panic. If you lose your head, you will not be able to think rationally and your chances of survival decrease. No matter how strange and disorienting your new environment is, no matter if you get attacked, no matter if you still have your phone – you have to remain calm and collected to get through it. Does everyone understand?"

The students nod as one.

"Great. Always keep that in mind. No matter the circumstances, heroes have to be able to think. Once you remember to calm yourself down, you must remain cautious and aware. Examine your surroundings carefully. Be ready for villains. But if someone approaches you, do not engage first – it might be an ambush, but they might be thinking the same thing. You never know if the first person you see is working with the one responsible for your space-time travel."

Midoriya mutters loudly while making notes in the background.

"The third thing is making a quick check for wounds and collateral damage – and your equipment. And yes, checking your phone is a very good idea. If you can't connect with anyone, it can be a good indication of time travel being involved. Checking the time and date on the internet is good too."

Uraraka gets a thumbs-up from Midoriya and Iida.

"In this scenario, let's assume your phone is broken, since it would be too easy. You do not know where you are, but you suspect you are no longer in the same city. What now? Mineta."

"Um... I would be looking for a newspaper?"

"Explain."

"It's a source of information, right? So you can check the place and date and stuff." After Aizawa turns away, he lowers his voice and finishes: "Also, there might be some hot pictures of-"

The range and accuracy of Asui's tongue is truly inspiring, as she slaps him from the other side of the room avoiding everyone else.

"Looking for sources of information is the next step, yes. Billboards or old newspapers are a good way to start. But what you should remember while you do? Hagakure."

"Stay calm!"

"Aside from that."

"Be careful?"

"And?"

"Well..."

"Let's say that based on today's newspaper, you discover you're one year in the past in the city of Tokyo. What is your first assumption about the type of time travel you're experiencing?"

"That it's the... closed loop?"

"And how do you know?"

"Because you said it's the most common one."

"Yes, but how do you know?"

"Um..."

"Does anyone have any ideas?"

There's silence.

"And that, is exactly my point. You must remember not to jump to conclusions. For example. Hagakure convinces herself that she's experiencing a closed loop time travel. So she goes to Principal Nezu and tells him she's one of our future students. Meanwhile, this is a differentiating parallel timeline, where Hagakure doesn't want to be a hero, but a musician. Still, the other Principal helps our Hagakure out and she returns to her proper timeline. All is well. But after registering the lack of their timeline Hagakure's application, Principal Nezu seeks out their Hagakure to find out why she didn't apply, and has a terrible accident on the way to her house."

Hagakure slumps in her seat in guilt at the hypothetical scenario. Shoji pats her on the shoulder.

"While no damage is done to our own timeline, and none are the wiser about the mistake – at least until someone asks the Principal if he remembers meeting Hagakure in the past... Through the infamous butterfly effect, there were horrible consequences to the differentiating timeline. Though it is unlikely that would actually happen, you must keep it in mind. Interfering in timelines is bad for everybody. So do not share any unnecessary information, especially about future achievements or relationships. And also, be careful before jumping to conclusions. Just because you think you know what kind of time travel you're experiencing, it doesn't mean you're necessary right."

Aizawa sighs.

"And lastly, once you have a hypothesis on where and when you might be, you have to estimate your chances of getting back. Luckily in most cases of time travel, it is temporary. In some it's so short you might return without even realizing you're outside of your own timeline – which is why caution and awareness are so important. There were few noted cases when the time travelers never returned, but there were usually complicated circumstances surrounding them and they were exceptions. In other words – leave the mechanics to specialists. Your main job is to not cause damage, and if help is inaccessible, staying safe as long as you can. If you're unfortunate enough that you can't make your way back for an extended period of time, then be careful not to cause suspicion. Making yourself familiar with the laws and customs of the new timeline or dimension is the first step in order to stay safe, so finding a free source of information such as a public library a gossip center are good choices to learn more about your surroundings."

The teacher looks at the clock. The class period is almost over.

"Are there any questions?"

Bakugo raises his hand.

"Yes, Bakugo."

"You seem suspiciously knowledgeable about all of this, even though you said this is top secret. Have you time traveled yourself or something?"

The rest of the class stares at him, blinking in surprise. Aizawa opens his mouth to respond, when the door opens without knocking.

"You forgot something," the person at the door throws him a fruit pouch. Aizawa catches, not at all surprised.

"Don't tell me... the fifth time?"

"Sixth, actually."

"Goddammit," Aizawa mutters rubbing his face in exasperation.

"Tell me about it," the second Aizawa rolls his eyes. "Keep an eye on the problem child."

"Isn't that a spoiler?"

"You know it isn't. It was obvious from the start."

"Thanks for the heads-up," the first Aizawa says sarcastically.

"No problem." The other Aizawa looks at the class full of gaping students. Some actually look close to fainting. "This is NOT an encouragement to recklessly time travel whenever you feel like it. I already know I'm in a closed loop, since I remember this happening. You better keep that in mind, because I really don't need additional motivation to expel all of you – especially since I almost did on a couple of occasions through the first year."

"Wait, **WHAT?!**" Class 1-A shouts in unison.

The bell rings, and the second Aizawa leaves, leaving the room in chaos.

The first Aizawa sighs in exhaustion. "I'm really too tired for this..."

The End.

* * *

**Author's Note:**

**I always wanted to post something about the different possible types of time travels. Then I thought – why not a class discussion? After all, this show has already dealt with space-time manipulation on multiple occasions: Mirio's quirk, Kurogiri's quirk, Eri's quirk, Nighteye's quirk...**

**Here's the list of what counts as space-time travel:**

**1) Across small distances (within the same city or region)**

**2) Across large distances (across regions or countries)**

**Forward:**

** 3) closed loop**

** 4) shadow reality**

**Backwards:**

** 5) closed loop**

** 6) shadow reality**

** 7) splitting into a new timeline**

** 8) same parallel timeline**

** 9) dynamic looping**

** 10) stacked looping**

** 11) Fusion realities/paradoxes**

**12) Differentiating parallel timeline/reality (same physics)**

**13) Different dimension (different powers systems, physics and/or species)**

**Rules for people experiencing unexpected/unauthorized space-time travel:**

**1\. Do NOT panic.**

**2\. Stay cautious and aware.**

**3\. Check for damage and remember to minimize the collateral upon arrival.**

**4\. Find sources about place and time, without leaking information.**

**5\. Be careful before jumping to conclusions.**

**6\. Estimate the chances of getting back safely.**

**Thank you so much for reading, please leave a review, follow and add the story to your favorites list if you can, but most importantly – read on, enjoy, and**** have a Very Merry Christmas!**** :D**


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